SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3be29685d125cda796151dd1a858849d798b78ec755419c295cddead11b9ebdd' 
  AND token = 'KnXQjS27SVuaoc6MNAif2o/KEbPkCMZZC5MZ2oXr/QY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}